The invention relates to an apparatus for cutting up biological sample material.
Apparatuses of the generic type are used in the examination of, in particular, solid biological sample material. This may be, for example, body tissue samples, but could also be other sample materials of biological origin having solid components.
As a rule, an examination presupposes that the sample material is present in homogenised form, for example in a buffer or the like. In the case of solid sample material, for example body tissue, the sample material must be cut up before the examination can occur.
An apparatus of the generic type which is used, in particular, for cutting up and homogenisation of cattle brain tissue in the context of BSE tests is known, for example, from WO02/48679.
The known apparatus has a sample container with a shaft disposed so as to be rotatable therein. The shaft is supported with one working end on the base of the sample container. A cutting device with a plurality of laterally projecting blades, which cut up sample material located in the sample container as the shaft rotates, is provided on the shaft in the region of its working end. At the other end of the shaft (coupling end), there is provided an externally accessible coupling member, which can be brought into coupling engagement with a complementary coupling member of a separate rotary drive device. The rotary drive device is designed in such a way that it can rotate the shaft at a relatively high speed (approximately 20,000 rpm).
In the known design, the coupling engagement is non-positive, in other words the rotary drive device or the complementary coupling member thereof presses from above onto the coupling end of the shaft. In order to minimize or to preclude the risk of any slippage, coupling must take place with a relatively high pressing force, with the consequence that the working end of the shaft likewise bears with a high pressure on the base of the sample container. In order to keep the friction which occurs here as low as possible, according to WO02/48679 a mounting is provided with a metal ball between the base and the working end of the shaft.
A disadvantage of the known apparatus is that in spite of the ball coupling, during operation an increased friction occurs in the region of the working end of the shaft, which can lead to difficulties.